1. Field of the Invention
The invention relates in general to methods and devices for small secondary batteries and the recharging thereof, and in particular, rechargeable hearing aid batteries and recharging appliances therefor.
2. Description of the Prior Art
As is well known in the fields where small batteries are used to power electronic devices, and in particular in the hearing aid field, secondary batteries require periodic recharging and primary batteries require frequent replacement. Previous primary batteries typically lasted no more than, for example, approximately one week in hearing aid appliances. Such replacement of primary batteries requires physical manipulation of the small batteries. However, those hearing-impaired persons needing an aid are often afflicted with arthritis or other ailments and may have trouble manipulating the small rounded battery into the case. In addition, many hearing aid wearers and other users often forget to purchase batteries, or find it inconvenient to go out to obtain them. Primary batteries also represent an ongoing expense, and many hearing-impaired persons, for example, are required to live on a rather stringent budget.
The use of a rechargeable cell or battery in a hearing aid device is known, but such previous expedients suffered from several shortcomings, and have generally not solved the above-mentioned problems satisfactorily. Previous secondary hearing aid batteries lacked sufficient energy density and thus could not power the hearing aid for an adequate length of time. Such previous secondary batteries with short discharge cycles were generally unsatisfactory. Also, the expense of such secondary batteries was prohibitive for many users.
Two types of rechargeable hearing aids had been previously proposed. The direct plug-in type required the wearer to plug a charger directly into a socket on the hearing aid, to apply recharging current directly to the battery. The inductively rechargeable type of hearing aid was simply dropped, battery and all, into a recharger appliance, which produced an alternating current magnetic field. This oscillating field was converted by appropriate circuitry in the hearing aid itself, into a direct current that recharged the hearing aid battery. These types of rechargeable aids and associated charging stations, are specialized devices that can not be used with a standard unmodified hearing aid. A standard hearing aid cannot be plugged in or inductively charged with such previous expedients. It would be of great benefit if high energy density secondary batteries mounted in conventional unmodified hearing aids could be remotely recharged either by induction or by radio frequency (RF) energy, or the like. The provision of secondary batteries that include recharging electronics within the battery would further benefit the art. The utility of a secondary hearing aid battery with a conventional unmodified hearing aid could be greatly enhanced by the provision of a recharging station where no handling of the battery outside of the hearing aid is necessary.
These and other difficulties of the prior art have been overcome according to the present invention.